Trains are used to transport a variety of different types of cargo, including granular or particulate bulk material such as feed, grain, soda ash, and sugar to name a few. Such bulk material is typically carried in hopper-style railcars which include at least one hopper discharge gate assembly. Hopper discharge gate assemblies are generally attached to the bottom of the railcar and include straight sidewalls and sloping end walls that together define a rectangular outlet opening. The gate assembly (or simply “gate”) is operable to controllably discharge the bulk material contained in the railcar. More specifically, the gate may be moved laterally between an open position and a closed position by the operation of a rack and pinion drive mechanism powered by an actuation shaft.
The actuation shaft normally includes one or more pinion gears supported by the frame of the gate. Rotation of the shaft about its axis causes lateral movement of the rack coupled to the gate door, thereby opening or closing the gate. The actuation shaft extends laterally outwardly beyond the gate and includes a handle or capstan at one or both ends. The capstans may include any of a plurality of different drive surfaces such as a drive recess or a drive periphery. The drive surface is engaged by a gate opener configured to rotate the actuation shaft and operate the gate.
As is known to those familiar with the industry, it is highly desirable to unload the contents of railcars as quickly (and safely) as possible. In a conventional unloading operation, a railcar is directed through (or parked in) an unloading station. As the railcar moves through the station, a power gate opener, such as a pneumatic gate opener, is moved along with the railcar on a parallel track. The power gate opener is aligned manually with the capstan of the gate, and actuated to rotate the actuation shaft. The bulk material then falls through the gate under the force of gravity and/or is vibrated using a vibrating device to assist the flow of the material through the gate. The falling material lands on a conveyor situated under the railcar and is transported to a storage or shipping location. After the material has been removed from the railcar, the gate opener is again used to close the gate by rotating the actuation shaft in a reverse direction. This process is repeated for the other gates on the railcar and for other cars moving through the unloading station.
Even in unloading stations where the railcars are stationary during unloading, the alignment of the gate opener with the capstan is a difficult task. Moreover, because of the heavy equipment involved, the risk of injury is very high. These concerns are increased when railcars are moved through the unloading station during the unloading process.